Fumigant mixture



Patented July 20, 1943 FUMIGANT MIXTURE William w. Allen and Joseph cor-1 Dawson, Midland, Mich., assignors to The Dow Chemical Company, Midland, Mich a corporation of Michigan &

No Drawing. Application October 14, 1941, l

' Serial N0. 415,408

4 Claims.

The present invention relates to new and improved fumigant mixtures and to a method for fumigating insect infested grain.

Many low boiling and Volatile organic liquids ther advantage resides in the fact that with such compositions the use of pressure containers and special applicators as required with methyl bromide alone is substantially eliminated. This rehave been suggested as fumigants, and carbon 5 suits from a lowering of the vapor pressure and tetrachloride, methyl bromide, ethylene chloride a reduction of the rate of vaporization attributaand the like are widely employed for the control ble to the large proportions of propylene chloride of insect pests. These compounds vary considemployed. ably as to physical characteristics whereby in The invention also provides a procedure wheremany instances the use of a given substance. is by grain stored in bins is treated withthe new limited to a particular type of fumigation procepropylene chloride-methyl bromide mixtures to v dure. obtain an economical and efllcient control ol -Withlncreased inventories of surplus grains, weevils, borers, and beetles. This procedure comthe control of weevils and related insect pests has prises introducing the fumigant mixture at the b co e a P m j r mp rtanceh top 01' a filled him-granary, elevator, etc. and stored grain is-generally held in bills or granaries onto the surface of the grain. The vapor presfor periods running from one season to several sures of the new mixtures are such that a gradual y s and r q t b come '80 bad y nfested distribution and penetration of the toxic vapor with weevils, beetles, and the like as to be of little occurs throughout the limits of the confining Value f r m n n mption; structure with the substantial absence of the un- Much time and money has been expended by desirable channelling efiect ordinarily observed t v nm n and pr vat a en i s n an with methyl bromide and the localized control ineflfort to evolve control methods for grain infestherent to propylene chloride. f ing insects. The amounts of many of the-known The amounts of the new compositions required Iumigants required to accomplish such control to accomplish control of insects at all levels Ofithfi a e so large that he co t trea nt s 'prostored grain are relatively small and it appears hibitive. Furthermore, the controls obtained that an effect is exerted by the mixture of toxiwith; such toxicants are frequ n ly erratic and cants which is much greater than the sum of the unsatisfactory even at relatively high concentratoxicities of the constituents. Thus from about tions due to variations in stored g ain tempera- 1 to about 3 gallons of the propylene chloridetures. and p o m of p ra n. vapor dismethyl bromide mixture per 1000 bushels of grain trlbuflon, n h nnell ng. give commercial control of insect pests. When According to the present invention, improved used alone, amounts of each constituent in excess fumisant mi tures are p v ded which comprise of those required in the mixture] frequently are as a major toxic ingredient a propylene chloride n t satisfactory. mixture containing a substantial amount oi The following table sets forth the results obmethyl bromide. The expression "substantial tained on corn ,with a representative propylene 1 amount as herein employed refers to from about chloride-methyl bromide mixture and with pro- 3 to'about per cent by weight. In view of the 'pylene chloride and methyl bromide alone. The disparity between the densities of propylene chlo- 40 organism concerned was Tribolium conjusum, i. e. ride and methyl bromide. on a volume basisthe the confused flour beetle. a

' v Table e Per cent eontrolatvariouslevels below Fumigant wagon r e r material bus is i sunset 1.5 it. at it. 4.51:. 0.51:. 9.6 it.

m g faflagf 2 me- 100 '100 100 v 100 100 1 Propyleneclilorido. 10.4 100 00 100 34 o 0 Methyl bromide... 5 l0 '0 d 8 2 100 propylene chloride predominates in such mixtures. These-new Ium'lgants have b'een found superior with respect to theircontrol of grain parasites, partic "'ly in bin f mlsatlons. 'A fur- In carrying 'out the migrations which resulted in'the foregoing data, cages containing a definite number oi test insects were introduced into a bin at the surface of and at diil'erent levels in the stored corn. The fumigants were applied at the top of the bin by sprinkling on the surface of the grain. Each bin was thereafter closed and allowed to stand for three days. The cages were then removed from the several levels and the degree of control calculated on the basis of observed insect mortality.

The following compositions are representative of preferred mixtures falling within the scope of the present invention.

Composition A Proplyene chloride 90 gallons Methyl bromide 10 gallons Composition B Propylene chloride; Carbon tetrachloride 22.5 gallons Methyl bromide 10 gallons If desired, other organic liquids may be incor- 67.5 gallons porated into the mixtures as disclosed to serve either as carriers for the propylene chloridemethyl bromide mixture or as added toxicants. Representative of such materials are ethylene chloride, trichloro ethylene, ethylene chlorobromide, propylene chlorobromide, chloroform, chloropicrin, ethylene oxide, etc.

We claim:

1. In a method for fumigating insect infested grain stored in bins the step of introducing 9. volatile fumigant comprising as a major toxic ingredient a mixture of propylene chloride with a substantial proportion of methyl bromide in the top of the bin and onto the surface of stored grain. I

2. A volatile liquid fumigant comprising a mixture of propylene chloride with a substantial proportion of methyl bromide.

3. A volatile liquid fumigant consisting of carbon tetrachloride and as a. major toxic ingredient a mixture of propylene chloride with a substantial proportion of methyl bromide.

4. A volatile liquid fumigant consisting of a. mixture of propylene chloride and methyl bromide, and a volatile liquid carrier therefor.

. WILLIAM W. ALLEN.

JOSEPH CARL DAWSON. 

